Method of making cellulose articles



Aug. 9, 1932. H. H. WRIGHT METHOD OF MAKING CELLULOSE ARTICLES Original Filed July 25 1925 NVENTOR A 'ITORNEY Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE HENRY H. WRIGHT, OF PASSAIC, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO DU PONT CELLOPI-IANE COMPANY, INQ, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE 1VIETHOD OF I/LBKING CELLULOSE ARTICLES Application filed July 25, 1925, Serial No. 46,159. Renewed May 20, 1930.

My invention relates to a method of forming shaped or moulded articles of cellulose or cellulose hydrate, such as, for instance,

boxes and cartons of different sizes and 5 shapes, or'bottle caps or caps to be placed over the mouth or neck of a bottle which, when dry, will form a bottle cap such as described in United States Letters Patent No. 823,355.

Heretoiore, articles of cellulose, such as bottle caps, have been made by the dipping process, such as described in United States Letters Patent No. 823,355. This is a laborious operation involving dipping round bot- 15 tomed tubes in a solution of cellulose or one of its derivatives, coagulating the solution and then removing the coagulated film from the tube. In the clipping process a thin ragged edge is formed which must be 30 trimmed off before the cap is suitable for use. This trimming process is a very laborious hand operation, since the caps collapse in the finishing process and the caps are left in their finished condition not exact but only approximating the size desired. In the man ufacture of boxes, cartons and the like from sheets of cellulose film an adhesive is necessary to hold the sheet in the desired form, or some method must be used for fastening together the sides of the article.

I have discovered that it sheets of a compound of cellulose, such as sodium or ammonium cellulose Xanthate, are formed into the shape desired and held in this shape while treated with a mineral acid, such as sulphuric acid, the article after reversion to cellulose hydrate holds indefinitely the shape that it possessed while being treated to revert the cellulose compound to cellulose hydrate. The wrinkles or crimps, that are put into the sheets of sodium or ammonium cellulose Xanthate and held while being treated with acid, retain their permanency after the reversion to cellulose hydrate is complete. When the article so formed is a box it may be left on the mould or may be retained in its desired shape until dry, as the cellulose sheet in its hydrated form shrinks as it loses its moisture, and upon shrinking the article takes the form of the mould. The shrinking removes substantially all of the wrinkles 0r crimps formed by the drying. lVhen the article formed is a bottle cap it is kept in its hydrated state until it is used. At that time it is placed on the bottle to be capped and it loses its moisture. The cap takes the form of the top of the bottle, hugging the top of the bottle closely and losing substantially all of the wrinkles or crimps, thereby leaving the cap in most instances entirely smooth, this depending, to some extent, upon the size of the top of the bottle, the length of the cap,

and the amount of shrinkage- Figure 1 illustrates a cap produced in accordance with my invention.

Figure 2 illustrates an apparatus used in the manufacture of the caps.

My invention is particularly advantageous in the manufacture of bottle caps. In making a bottle cap to fit an ordinary milk bottle with a neck of a diameter of 2 or a jar or tumbler of the same diameter, or, for that matter, any other container that it is desired to cap, a solution of sodium cellulose xanthate in water, i. e. a sheet of viscose, is cast in the form of a sheet of suitable thickness and coagulated in a neutral salt solution. Such a solution may be a solution of ammoniasulphate, sodium sulphate or sodium chloride or any other salts known to coagulate viscose solutions. The resulting product is a sheet of sodium or ammonium cellulose Xanthate or probably a mixture of the two if ammonium sulphate is used.

This material is cut into circular discs about 4 in diameter and the discs placed over a die 1, Fig. 2, having a circular hole 2 approximately 3 in diameter with the center of the disc in line with the center of the hole. A plunger 8, as shown in Fig. 2, about 2%" in diameter forms the cap. This dieing operation causes the edge of the disc to crimp uniformly around the plunger forming a cap 4 having a crimped skirt 6 such as is shown in Fig. 1. This cap of sodium or ammonium cellulose Xanthate, while being held in its crimped shape, is treated with mineral acid, such as sulphuric acid. In a few minutes the sodium or ammonium cellulose Xanthate reverts to cellulose hydrate. After this treatment is complete, it will be found that the cellulose has gripped around the plunger from which it can be removed without effort. After the cap is washed free of acid, it may be used as a cap for a bottle or jar as above described by placing it over the mouth or neck of the bottle or jar and allowing the moisture to evaporate. After the moisture evaporates, the cap assumes the contour of the neck of the bottle. The wrinkles or crimps of the skirt disappear and the cap will fit snugly over the bottle and conform to the contour of the bottle neck.

In addition to the fact that bottle caps may be manufactured more economically by this method, the caps made by this process are superior to the caps made by the dipping process, especially for wide mouth bottles or jars, as the cap is exactly the shape of the top of the bottle or jar and is easily affixed thereto. Caps formed by the dipping process on round bottomed moulds collapse by handling in the washing and trimming operation and must be opened by the person applying the same before being affixed to the bottle.

In making boxes by this process a cap, similar to the one described above for a. bottle cap, may be dried on a suitable form of the shape of the box desired. \Vhen dry, it is removed from the form, the resulting article being in the shape of a box without a cover. The cover is made by the same method. If a circular or rectangular box is desired, it is simply necessary to change the shape of the die or mould used to hold the sheet of sodium or ammonium cellulose xanthate in the form desired while reverting to cellulose with acid.

It is obvious that other methods of bolding the sheets of sodium or ammonium cellulose xantliate in the shape desired while reverting to cellulose with acid, other than holding on a die, may be employed. It is not intended to limit this invention to any particular method of shaping the material, as any method that will hold a sheet of sodium cellulose Xanthate in the desired form. while treating it with acid may be used with equal advantage.

In the manufacture of bottle caps it is desirable to have on the cap a device for readily removing the cap from the bottle without the necessity of cutting it. Such a device may be a tab 5, such as is shown in Fig. 1. which will not shrink in tight to the neck of the bottle. By pulling this tab a tear may be started in the cap which will loosen its grip on the bottle so that it may be readily removed. To accomplish this, when cutting the circular disc for forming the cap a V- shaped projection about long and about wide is left projecting from the circumference of the circular disc.

The articles of celluose made in accordance with this invention may he made resistant to water; for example, there may be added to the cellulose solution before it is formed into sheets, salts of fatty acids, such as sodium. or potassium stearate. In this case, after the article is treated by the acid to revert it to cellulose, there will be in intimate contact with the cellulose hydrate a fatty acid. Gelatine may also be added to the cellulose solution before it is made into sheets, and the finished product after reverted to cellulose may be treated with any of the reagents known to render gelatine insoluble. Another method for rendering the resulting product resistant to water is to make a parafiin emulsion with the cellulose solution before it is made into sheets. This may preferably be done by dissolving the paraflin in one of its solvents and by the use of commercial emulsifiers make an emulsion with water. In this emulsion the cellulose derivative may be dissolved, the resulting emulsion being an emulsion of paraffin with a solution of cellulose or a cellulose derivative.

Having thus described my invention, I claim:

1. A method of forming cellulose articles which consists in moulding the article from a sheet of a cellulose xanthate and reverting the cellulose xant-hate to cellulose hydrate while maintaining the article in its desired shape.

2. A method of making cellulose articles which consists in forming the article into the desired shape from a sheet of a cellulose xanthate and reverting the cellulose xanthate to cellulose hydrate while the article is still in the die.

3. A method of making cellulose articles which consists in forming the article into its desired shape from a sheet of a cellulose xanthate and treating the cellulose xanthate with a mineral acid while maintaining the article in its desired shape.

4. A method of making cellulose articles Which consists in forming the article into its desired shape from a sheet of a cellulose xan thate and treating the cellulose xanthate with a mineral acid while the article is still retained in the die.

5. A method of making cellulose articles from a sheet of a cellulose xanthate which consists in forming the article in its desired form and treating the article with sulphuric acid while maintaining the article in its desired shape.

6. A method of making cellulose articles which consists in dieing out a blank from a sheet of a cellulose Xanthate, moulding the blank into the desired shape, and treating the cellulose Xanthate with sulphuric acid while retaining the article in its desired shape.

7 A method of forming a bottle cap which consists in dieing out a disc having a tab from a sheet of a cellulose xanthate, moulding the disc into the shape desired, and treating the moulded cap with sulphuric acid to revert it to cellulose hydrate While retaining the cap in its desired form.

8. A method of forming a cellulose article which consists in forming the article from a sheet of cellulose Xanthate containing an ingredient adapted to increase its resistance to Water and reverting the cellulose compound to cellulose hydrate.

9. A method of forming a cellulose article Which consists in molding the article from a sheet of cellulose xanthate and reverting the cellulose xanthate to cellulose hydrate.

In testimony whereof, I have afiixed my signature to this specification.

HENRY H. WRIGHT. 

